Objects are the core building blocks of our auditory-perceptual world. However, when our current understanding of auditory-object processing is compared to the putative steps needed to process auditory objects, it is clear that there are key gaps in our knowledge. The most fundamental and important gap is our lack of understanding of the relationship between the acoustic features of an auditory stimulus, neural activity, and perception. Indeed, what we know of this relationship is lacking at the most fundamental level: the manner in which stimuli are integrated and segregated into one or more perceptual auditory objects. Two key innovations of this proposal are designed to fill this gap in our understanding. First, the PI directly tests the relationship between the acoustic features of auditory stimuli, single-neuron activity, and subjects'behavioral reports of auditory-object integration and segregation. Second, the PI records and contrasts neural correlate of auditory-object processing in both the primary auditory cortex and the secondary auditory cortex (i.e., the anterolateral belt). Aim #1 tests whether neurons in the auditory cortex code for (1) the acoustic features of an auditory stimulus, or (2) the monkeys'behavioral reports of auditory-object integration and segregation. This Aim is achieved by evaluating the hypothesis that neural activity in the primary auditory cortex is reliably modulated by the acoustic features of an auditory stimulus but is not modulated by the subjects'behavioral reports. In contrast, it is also hypothesized that neural activity in the secondary auditory cortex (the anterolateral belt) is reliably modulated by the subjects'behavioral reports but is not modulated by the acoustic features of an auditory stimulus. Both hypotheses are tested by recording extracellular from neurons in the auditory cortex while monkeys participate in a one-interval, two-alternative-forced-choice task that requires them to listen to an auditory stimulus and report whether they hear one or two auditory objects. PUBLIC HEALTH RELEVANCE: This line of research has important clinical ramifications. From the data that emerge from this proposal, a greater appreciation of the neural mechanisms and processes that underlie auditory-object processing will emerge. This enhanced appreciation will provide important insights into hearing dysfunction and disorders in speech perception. Ultimately, the insights from these studies will improve the design of hearing prosthetics, diagnostic assays, and the development of rehabilitation programs.